Golimumab for the treatment of psoriatic arthritis

Abstract

This paper presents a summary of the evidence review group (ERG) report into the use of golimumab for the treatment of psoriatic arthritis (PsA). The main clinical effectiveness data were derived from a single phase III randomised controlled trial (RCT: GO-REVEAL) that compared golimumab with placebo for treating patients with active and progressive PsA who were symptomatic despite the use of previous disease-modifying antirheumatic drugs or non-steroidal anti-inflammatory drugs. The 14-week data showed that, compared with placebo, golimumab 50 mg significantly improved joint disease response as measured by American College of Rheumatology (ACR) 20 [relative risk (RR) 5.73, 95% confidence interval (CI) 3.24 to 10.56] and Psoriatic Arthritis Response Criteria (PsARC) (RR 3.45, 95% CI 2.49 to 4.87), and skin disease response as measured by the Psoriasis Area and Severity Index (PASI) 75 (RR 15.95, 95% CI 4.62 to 59.11). The 24-week absolute data showed that these treatment benefits were maintained. There was a significant improvement in patients’ functional status as measured by the Health Assessment Questionnaire (HAQ) change from baseline at 24 weeks (–0.33, p < 0.001). The open-label extension data showed that these beneficial effects were also maintained at 52 and 104 weeks. However, PASI 50 and PASI 90 at 14 weeks, and all of the PASI outcomes at 24 weeks, were not performed on the basis of intention-to-treat analysis. Furthermore, analyses of the 24-week data were less robust, failing to adjust for treatment contamination due to patient crossover at week 16. The manufacturer conducted a mixed treatment comparison (MTC) analysis. The ERG considered the assumption of exchangeability between the trials for the purpose of the MTC analysis to be acceptable, and the statistical approach in the MTC analysis to be reliable. Regarding the safety evaluation of golimumab, the manufacturer failed to provide longer-term data or to consider adverse event data of golimumab from controlled studies in other conditions, such as rheumatoid arthritis and ankylosing spondylitis. Although the adverse effect profile of golimumab appears similar to other anti-tumour necrosis factor (TNF) agents, the longer-term safety profile of golimumab remains uncertain. The manufacturer’s submission presented a decision model to compare etanercept, infliximab, golimumab and adalimumab versus palliative care for patients with PsA. In the base-case model, 73% of the cohort of patients were assumed to have significant psoriasis (> 3% of body surface area). Estimates of the effectiveness of anti-TNF agents in terms of PsARC, HAQ change and PASI change were obtained from an MTC analysis of RCT data. The manufacturer failed to calculate incremental cost-effectiveness ratios (ICERs) correctly by comparing golimumab with palliative care instead of the most cost-effective alternative (etanercept). Despite the manufacturer’s claim that golimumab is a cost-effective treatment option, the manufacturer’s own model showed that golimumab is not cost-effective compared with other biologics when the ICERs are correctly calculated. None of the sensitivity analyses carried out by the manufacturer or the ERG regarding uncertainty in the estimates of clinical effectiveness, the acquisition and administration cost of drugs, the cost of treating psoriasis and the utility functions estimated to generate health outcomes changed this conclusion. However, a key area in determining the cost-effectiveness of anti-TNF agents is whether they should be treated as a class. If all anti-TNF agents are considered equally effective then etanercept, adalimumab and golimumab have very nearly equal costs and equal quality-adjusted life-years (QALYs), and all have an ICER of about £15,000 per QALY versus palliative care, whereas infliximab with a higher acquisition cost is dominated by the other biologics.